IOP Changes With Different Anesthetic Agents During Laparoscopic Colorectal Surgery

Overview

This study is aimed to evaluate how intraocular pressure (IOP) is changed depending on surgical position (Trendelenburg versus reverse Trendelenburg) in the same patient and to compare the effects of different anesthetics on IOP (desflurane versus propofol) in patients undergoing laparoscopic colorectal surgery. The study design is a double-blind randomized controlled trial. The patients were randomly assigned to desflurane or propofol administrated groups and all patient are administered intravenous remifentanil continuously as adjuvant analgesics during anesthesia. For this study 50 to 80-year-old patients undergoing laparoscopic colorectal surgery without eye disease were enrolled. Mean arterial blood pressure, peak airway pressure, end tidal carbon dioxide, and IOP (using a Tono-pen® Avia tonometer) on both eyes were measured at defined intervals during the procedure.

Perioperative visual loss is a rare but devastating complication associated with certain type of operative procedures. Laparoscopic or robotic surgeries for colorectal cancer, prostate cancer and diseases of the female genital organs in the pelvic cavity are performed in a steep Trendelenburg position and pneumoperitoneum, which increases the intraocular pressure (IOP) by 13-26 mmHg compared with the preoperative IOP value. High intraocular pressure is believed to correlate with decreased perfusion to the optic nerve, and thus could lead to ischemic optic neuropathy. The objective of the study is to test which anesthetic agent (desflurane or propofol) can attenuate the changes in IOP during laparoscopic colorectal surgery and identify correlated parameters. Fifty patients (30-80 years; American Society of Anesthesiologists' physical status 1-2) scheduled for laparoscopic colorectal surgery will be enrolled and allocated randomly into two groups (group D and group P). After measurement of initial IOP with topical opthalmic anesthetics, general anesthesia will be induced with pentothal sodium 5-6mg/kg (group D) or propofol (group P) 2-2.5mg/kg. After administration of muscle relaxant and intubation, intraocular pressure will be measured and anesthesia will be maintained with desflurane (group D) or propofol (group P) and all patients will be administered intravenous remifentanil concurrently during anesthesia. During anesthesia, IOP will be measured at different patient positions. At the time of each IOP measurements, the following data set will be collected: mean arterial pressure (MAP), End tidal carbon dioxide (EtCO2), peak inspiratory pressure (PIP).